Set container collector prefix based on owner property

[jsturtevant]

This updates the container_id label for the metrics reported by the container collector to use the owner ref which is set by docker and containerd respectively.

When running the windows_exporter with the container collector running with a containerd runtime the output of the metrics prefixes the metrics container_id label with docker:// but it should be containerd:// to match other tooling.

Current output:

windows_container_available{container_id="docker://130d82553c53d017649b7115a4e58a8007eef0641ce8804bfb6eb7dcc70ef18b", instance="10.240.0.65:5000", job="windows-exporter"}

If you use hcsdiag list on the host to see the owner ref it specifies the containerd shim as the owner:

hcsdiag list
130d82553c53d017649b7115a4e58a8007eef0641ce8804bfb6eb7dcc70ef18b
    Windows Server Container,   Running,                                     , containerd-shim-runhcs-v1.exe

This is important for jobs that match against container_id to gather more stats from tools like kube-state-metrics which specifies containerd for the contianerid:

kube_pod_container_info{container="iis", container_id="containerd://130d82553c53d017649b7115a4e58a8007eef0641ce8804bfb6eb7dcc70ef18b", image="mcr.microsoft.com/windows/servercore/iis:windowsservercore-ltsc2019", image_id="mcr.microsoft.com/windows/servercore/iis@sha256:4763a2b3029259a9fd05168d3963493cbf245b535e02dc80e1eaf1dc51645a05", instance="10.240.0.39:8443", job="kube-state-metrics", namespace="default", pod="iis-1809-668c5b9c87-t5z66"}

For example, a promethues rule from the kubernetes-mixin project:

windows_container_available{%(wmiExporterSelector)s} * on(container_id) group_left(container, pod, namespace) max(kube_pod_container_info{%(kubeStateMetricsSelector)s}) by(container, container_id, pod, namespace)
            ||| % $._config,

[breed808]

Thanks for submitting this James!
I've included a couple minor comments, have a look and let me know if there's any issues.

[breed808]

Looks good!